摘要
采用微合金化Ml—Mg—Mn—Sc—Zr合金焊丝按MIG方法焊接7A52铝合金板材。采用高功率X射线衍射仪对7A52铝合金焊接接头不同部位进行了精确的X射线衍射分析。结果表明,在焊接接头中存在四个本质的热扩散区域。离焊缝中心线0~4mm范围为焊缝区,焊缝中心为铸态组织;4~10mm区域为半熔化区,在自然时效过程中有较多微小的强化相η'析出;10~16mm范围为淬火区,原有沉淀相部分地回溶到基体并不能在自然时效过程中重新析出;最远端为软化区,基材中原有强化相叩在焊接热输入的影响下形成了粗大的T相,导致强度降低。焊接热输入对不同区域的影响大小不同,导致不同区域的固溶程度和晶格畸变量不同,从而使微观和宏观残余应力都略有差异。
7A52 alloy plate was welded by means of MIG(metal inert-gas) welding using Al-Mg-Mn-Sc-Zr micro-alloyed wire.The specimens cut down at different regions of the welded joint were diffracted accurately by high-power X-ray diffractometer.The results showed that there are 4 different heat diffusion zones in the welded joint,these zones had themselves substantive characteristics.The first was the weld,and it was the α-Al matrix as cast structure distanced the weld centre line about 0-4 mm.The second was the semi-melted zone,and it distanced the weld centre line about 4-10 mm.The nanocrystalline η′(MgZn2) phase and Al6Mn re-precipitated in nature ageing process when it was laid at room temperature.The region distanced the weld centre 10-16 mm was the low temperature solution zone,and the strengthening phases redissolved into α-Al matrix partly at the weld temperature but could not re-precipitate at room temperature.The fourth was a soften zone.In this zone,the strengthening phase growth and formed the T phase.It was the reason of strength decreasing.Because the effects of welding heat on zones were different,it lead to different solid solubility,distortion of lattice,the micro-strains and residual stress.
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2007年第12期13-17,共5页
Transactions of The China Welding Institution
基金
国家重点基础研究计划(973)项目(2005CB623705)
关键词
铝合金板材
焊接
析出
晶粒尺寸
残余应力
aluminum alloy plate
welding
precipitation
grain size
residual stress